Radio receiving apparatus



Feb. 12, 1929. 1,702,067

P. W. WILLANS RADIO RECEIVING APPARATUS Filed Jan. 19, 1925 INVENTOR PETER WILLIh WILLANS 94 4 (la/W V ATTORNEY Patented Feb. 12, 1929.

UNITED srarns e at er mm PETER WILLIAM WILLANS, OF NORI'IIAMPTONSHIRE, ENGLAND, ASSIGNOB. T9 RADIO CORPORATION OF AMERICA, A CORPOBATIUN O1 'DELAW'ARE.

RADIO RECEIVING APPARATUS;

Applicationfiled January 19, 1925, Serial No. 3,209, and in Great BritaiuI ebruaryiG, 1924:-

This invention relates to radio receiving apparatus and especially to apparatus for receiving modulated v'aves, particularly waves modulated by telephone currents.

it well recognized that when the amount of reaction in a regenerative receiver is increased distortion occurs in the reception of a regenerative receiver, means in the audio frequency stage which will increase the amplitude of the higher side-tones, the amplitude of which has been decreased owing to the reaction, more than the amplitude of the lower side-tones, which have been comparatively unaffected by the reaction.

In order to obtain this result I employ in the audio frequency stage a circuit having in it impedances one at least of which is such that the potential fall across it produced by the higher frequencies, which have been reduced in amplitude owing to the reaction, is greater than that which would be produced by the lower frequencies of the same a1nplitude. 7

Theoretical considerations tend to show that the best arrangement 15 to employ in the anode circuit of the regenerative valve an inductance and a resistance in ser1es, these two elements being connected between ,the

grid and filament of an amplifying valve,

and that the constants of the circuits should be so chosen that the ratio of the said resistance to the said inductance should be equal to half the ratio of the lumpedresistanceof the input circuit of the regenerative valve to the inductance of that input circuit. If this is done, the effect of the higher audio frequency distortion in the regenerative valve will be exactly compensated by the increase in audio frequency amplification of the higher frequencies in the audio frequency amplifier.

Such an arrangement is shown in the single figure of the drawing in which 1 is a regenerative valve and 2 an amplifying valve. The input circuit of 1 is composed of an inductance L and condenser C, the lumped resist ance of said circuit being represented by a resistance R. Regeneration in this valve is obtained by an inductance L in the anode circuit of valve 1 coupled to the inductance L in the grid cathode circuit of 1. In the anode circuit of valve 1 and across the grid and filament of valve 2 are connected a resistance R and inductance L which are shunted by a small condenser O acting as a high frequency by pass, the impedance of which to low frequency currents can be reckoned as large compared with R and L The 7 required correction is obtained by making the ratio of R and L half that of the effective resistance of the circuit C L (taking reaction into account) to L. That is the constants should be so chosen that Ohmic resistance R Effective resistance CLR inductance L 2a: inductance L and in. what manner the same is to be per-- formed, I declare that what I claim 1. The combination of a three electrode vacuum tube having cathode, anode and control electrodes, an input circuit connected between the cathode and control electrodes,

an output circuit connected between the cat-hode and anode electrodes and coupled to the input circuit sufiiciently close to produce selectivity which reduces the amplitude of sidehands corresponding to higher tones, said VII cathode-anode circuit having a capacity element in parallel with serially connected resistance and inductance elements of such a hand frequencies.

.value thatsubstantially uniform potential an input circuit having an inductancevL, a

resistanceR and a capacity C in parallel with said inductance and resistance, connecting said grid and cathode, an output circuit hetween said anode and cathode, nieans for v causing said output circuit to react on said input circuit, and means including a resistance R and inductance L in saidoutput circuit, so

proportioned that the resistance of 3 divided by the inductance 'of L equals the effective resistance of CLR divided by the inductance of 2L, for insuring uniform potential drop across the resistance and inductanceyin SELlCl output circuit at all frequencies.

3. In a regenerative receiver a vacuum tube having inputand output circuits,"an inductance and resistance shunted'by a capacity in said input circuit, means for coupling said output circuit and said input circuit to produce regeneration, and means in said output circuit adapted to control the input circuit of an amplifier including-a series resistance and inductance so proportioned With reference to the capacity shunted elements in sa d input circuit that'the amplitudeot the potential drop across said series resistance and inductance Wlll be uniform at all frequencies PETER WILLIAM VWIVLLANS;A 

